Colonel Gaddafi successfully concealed stockpiles of chemical weapons from the world, the organisation that oversees a global ban on chemical weapons has confirmed.

A team from the Organization for the Prohibition of Chemical Weapons (OPCW) that visited Libya this week from 17 to 19 January 2012 found "sulfur mustard agent" and other munitions including artillery shells.

The post-Gaddafi government in Tripoli announced the discovery last year and submitted a formal declaration of the weapons to the OPCW on 28 November.

According to the OPCW the newly declared weapons are stored at the Ruwagha depot in southeastern Libya, together with quantities of sulfur mustard and precursor chemicals that were declared by the Gaddafi regime when Libya joined the OPCW in early 2004.

Gaddafi's pledge to surrender any chemical weapons in his possession was key to efforts in 2004 to normalise relations between Libya and the West.

Former prime minister Tony Blair played a key role in bringing Gaddafi in from the cold, the confirmation that the regime concealed chemical weapons from the West suggests the-then prime minister was duped by the dictator.

Speaking in November last year, Blair defended his approach to the old Libyan regime. "He was developing a nuclear and chemical programme," he said. "He gave it all up."

But that claim now appears to be mistaken.

Libya must now submit a detailed plan and completion date for destroying all of the declared materials to the OPCW not later than 29 April 2012.